Conventionally, a monitoring camera apparatus (surveillance camera apparatus) is installed above a camera installation site such as on a ceiling of a building or on an outdoor pole and captures images of a monitoring area below. The captured images are sent to a remote monitoring apparatus and displayed on a monitor. Monitoring camera apparatuses equipped with a tilt/pan rotating mechanism are known. A monitoring camera apparatus which has a function to track a subject such as a person by image processing has also been proposed. Such a conventional monitoring camera apparatus is disclosed, for example, in Japanese Patent Laid-open No. 2002-247424 (Page 3, FIG. 1, etc.).
However, conventional monitoring camera apparatuses are sometimes inconvenient because no information is available about installation height of the cameras above floor surfaces, road surfaces, and the like at the installation site. For example, when captured images are displayed on a monitor, it is not easy to get accurate information about subjects on the monitor because the installation height of the camera is unknown. Also, for example, subject detection based on captured images does not allow for differences in size among the subjects according to the installation height of the camera. This can degrade detection accuracy, resulting in false detection. Besides, false detection of subjects will affect performance of additional functions such as a tracking process.
To solve the above problems, it is conceivable to enter camera installation height manually or install a special sensor for use to detect the camera installation height. However, this will require labor and complicate configuration.